Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon.
Multiple gate field-effect transistors (MuGFETs) are a recent development in semiconductor technology which typically are metal oxide semiconductor FETs (MOSFETs) that incorporate more than one gate into a single device. The multiple gates may be controlled by a single gate electrode, where the multiple gate surfaces act electrically as a single gate, or by independent gate electrodes.
One type of MuGFET is referred to as a FinFET, which is a transistor structure with a fin-like semiconductor channel that is raised vertically away from the silicon surface of an integrated circuit. A recent design for FinFETs is a gate-all-around (GAA) FinFET, which has a gate material that surrounds a channel region on all sides.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.